The present invention relates to frequency scanning radio receivers. More particularly, the present invention relates to automatically programming the receiving frequencies of a frequency scanning radio receiver to frequencies on which signals are broadcast in the geographical location of the receiver, even if the receiver is continually moved to different locations.
Conventional frequency scanning radio receivers monitor radio transmissions by continually tuning the receiver, i.e., scanning, a group of discrete frequencies. When a transmission is detected on a frequency to which the receiver tunes, and the transmission signal level exceeds a threshold, tuning stops and the transmission is monitored. All radio receivers can only receive transmissions within a limited geographic area. The transmissions of usual interest to listeners using frequency scanning receivers are, for example, police, emergency medical services, fire, and public service agencies, assigned to discrete frequencies. Other local transmissions, for example, transmissions from local businesses, may not be of interest to these listeners. Therefore, a listener must determine the frequencies of interest that are to be monitored and tune or program the frequency scanning receiver so that only those frequencies are monitored.
Historically, scanning radio receivers have been manually programmable, i.e., a listener manually inputs to a memory in the receiver the frequencies to be monitored. The frequencies of interest are established by experience, from Federal Communications Commission (FCC) license records, by purchase of channel listings from a private source, or otherwise. Privately published frequency allocations are frequently out-of-date.
Manually programming a radio receiver to monitor selected channels is an onerous and time consuming task that is subject to data entry errors. Programming a radio receiver involves consulting an owner's manual, and manually entering programming data and each frequency to be monitored using an input device, such as a keypad.
A frequency scanning radio receiver requires reprogramming whenever the listener changes geographic areas. The difficulty and time required to program and reprogram a conventional scanning radio receiver has led to listener frustration and is a major cause of return of frequency scanning radio receivers to retailers and manufacturers for refunds. Accordingly, there exists a need for a frequency scanning radio receiver that overcomes the problems of manual programming of frequencies of interest.